1. Field of Invention
This invention relates to an apparatus and method for cleaning wish ozone, and more particularly, to a system for treatment with ozone so that hazardous solvents that are currently used in the cleaning process are reduced or eliminated.
2. Background of the Invention
A dry cleaning process for laundry is similar to the wet cleaning process for laundry except that in contrast to the wet cleaning process, the dry cleaning process uses solvents instead of water. Typically, as the laundry is agitated in a dry cleaning machine, there is a constant flow of clean solvent from a pump and filter system. The dirty solvent is continuously being removed from the machine and recirculated through a filter and back to the dry cleaning machine during the agitation cycle.
After completion of the agitation cycle, the laundry will go though a drying cycle to remove the solvent from the laundry. A spin cycle is used to first remove a substantial amount of the solvent from the laundry through centrifugal force that is generated by rapidly rotating the laundry. The laundry is then exposed to circulating dry air to remove any remaining trace amounts of solvent. The remaining fumes of solvent are collected and condensed over cooling coils. Any water moisture that may have been introduced into the dry cleaning process is also removed from the solvent prior to reuse of the solvent.
Perchloroethylene (PERC or PCE), a potential human carcinogen, is the most commonly used dry cleaning solvent. Air releases of PERC and petroleum solvents used to clean fabrics are the primary environmental release from dry cleaning. Groundwater contamination by the solvents can also occur through spills and inadequate storage and drain disposal. Improper disposal of solvent laden material, such as filters, can also contribute to environmental contamination.
Exposure to the solvents commonly used in dry cleaning shops can occur through skin absorption, eye contact, or inhalation of the vapors. Symptoms associated with exposure include depression of the central nervous system, damage to the liver and kidneys, impaired memory, confusion, dizziness, headache, drowsiness, and eye, nose, and throat irritation.
It has been estimated that there are approximately 34,000 commercial dry cleaners that process a total of approximately 825,000 tons of clothes per year (USEPA 1991b). Accordingly, what is needed in the art is to reduce or eliminate the use of hazardous solvents that are used during the dry cleaning process for laundry.
The application of ozone in the wet cleaning process for laundry has been recognized and used extensively. The typical wet cleaning process for laundry uses water, bleaching agents and detergents. Ozone can be substituted in the wet cleaning process for the detergents and bleaching agents. Ozone is a powerful oxidant that can be used as the primary disinfecting, cleaning and bleaching agent in the wet cleaning process for laundry.
Similarly, continuing efforts are being made to improve dry cleaning apparatus and methods through the use of ozone. By way of example, note U.S. Pat. Nos. 5,511,264 and 5,488,842 to Nishioka et al. U.S. Pat. No. 5,511,264 discloses a method for deodorizing and refreshing dry cleaning petroleum group solvents using ozone and U.S. Pat. No. 5,488,842 discloses an apparatus using such a method, which can maintain the circulating solvents in a fresh condition for a long time. The apparatus and method of Nishioka et al. does not teach a mechanism by which dry cleaning solvents are reduced or eliminated.
U.S. Pat. No. 5,996,155 to Chao et al. discloses a dry cleaning process that uses liquid carbon dioxide and not hazardous solvents. However, Chao et al. teaches that carbon dioxide will only exhibit liquid-like properties under pressure and although hazardous solvents are eliminated, the costs to retrofit existing dry cleaning equipment would be high in comparison to using water with dissolved ozone.
U.S. Pat. Nos. 5,960,501 and 5,960,649 to Burdick, U.S. Pat. No. 6,006,387 to Cooper et al., and U.S. Pat. No. 5,625,915 to Radler et al. disclose a wet cleaning system and method for treating laundry with ozone. The aforementioned teachings do not provide a mechanism by which there is enough dissolved ozone available to meet the demand of the soiled laundry and maintain a desired dissolved ozone concentration. Specifically, previous systems typically furnish low levels of ozone because ozone is injected in the return line of the washer.
Another grouping of background patents are those patents that disclose the addition of ozone to the water prior to use in a wet cleaning washing machine. By way of example, see U.S. Pat. Nos. 5,097,556 and 5,181,399 to Engel et al., U.S. Pat. No. 5,656,246 to Patapoff et al. and U.S. Pat. No. 5,493,743 to Schneider et al. that teach closed loop ozonated wash water systems. Similarly, U.S. Pat. No. 5,409,616 to Garbutt et al. teaches a method and apparatus that recycles used wash water by way of a closed loop system using ozone as a cleaning agent.
U.S. Pat. No. 3,065,620 to Houser and U.S. Pat. No. 5,313,811 to Wasinger et al., disclose a mechanism by which ozone may be injected directly into the wet cleaning washing means. U.S. Pat. No. 5,763,382 to Cooper et al. discloses a cold water washing formula and method that includes ozonated water.
Another grouping of background patent are those patents that disclose a system and method for generating ozonated water. Note U.S. Pat. Nos. 5,939,030 and 6,153,151 to Moxley et al.
Notwithstanding the existence of such prior art laundry apparatus and methods, there is a need for an improved and more efficient apparatus and method for using dry cleaning machines to clean laundry that will achieve the requisite level of cleaning without having harmful effects on persons and the environment It is, therefore, to the effective resolution of the aforementioned problems and shortcomings of the prior art that the present invention is directed.
However, in view of the prior art in at the time the present invention was made, it was not obvious to those of ordinary skill in the pertinent art how the identified needs could be fulfilled.
The present invention provides a method for cleaning with ozone comprising the steps of establishing a predetermined ozone concentration for cleaning, providing an ozone generating means, dissolving ozone generated by the ozone generating means into a contained body of water, measuring the ozone concentration in the body of water, dissolving ozone into the contained body of water until the predetermined ozone concentration level is attained, supplying the ozonated water from the body of water to a contained wash, measuring the ozone concentration of the contained wash, and recirculating water from the wash to the body of water to substantially maintain the measured concentration of ozone in the contained wash at the predetermined ozone concentration.
The key to successfully utilizing ozone in the cleaning process is to ensure sufficient dissolved ozone in the wash water to meet the demand from the washing machine. It is not sufficient to simply generate higher levels of ozone gas, rather, it is necessary to ensure the ozone goes into solution and is maintained at a constant concentration.
It is therefore an object of the present invention to provide an improvement that overcomes the aforementioned inadequacies of the prior art and provide a significant contribution to the advancement of cleaning laundry.
Another object of this invention is to provide a method and means to use a dry cleaning machine that permits the introduction of high levels of dissolved ozone into the circulating water.
Another object of this invention is to provide a method and means to use a dry cleaning apparatus with ozone as the cleaning agent and a method that reduces or eliminates the use of hazardous solvents such as PERC.
It is to be understood that both the foregoing general description and the following detailed description are explanatory and are not restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute part of the specification, illustrate embodiments of the present invention and together with the general description, serve to explain principles of the present invention.
These and other important objects, advantages, and features of the invention will become clear as this description proceeds.
The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts that will be exemplified in the description set forth hereinafter and the scope of the invention will be indicated in the claims.